Automatic thread clipper for bag end sewing machines



July 31, 1962 H. K. FOX 3,046,919

AUTOMATIC THREAD CLIPPER FOR BAG END SEWING MACHINES Filed NOV. 27, 1959 3 Sheets-Sheet l INVENTOR. HAROLD K. Fox

ATTORNEYS July 31, 1962 H. K. FOX 3,046,919

AUTOMATIC THREAD CLIPPER FOR BAG END SEWING MACHINES Filed Nov. 27, 1959 3 Sheets-Sheet 2 IN V EN TOR.

F76. 5 HAROLD K. Fox

ATTORNEY:

July 31, 1962 H. K. FOX 3,046,919

AUTOMATIC THREAD CLIPPER FOR BAG END SEWING MACHINES Filed Nov. 27, 1959 5 SheetsSheet 3 FIG.@

IIIIIHIIIJJIJIIFH (lhlllll lllllllllllllilllfl F267 15 37 il Nil! C-IIIHHIHH IIIIIHIHIH A i cmmlmn IIUIIHIIIH H IN I Q? Fki [lllllllll lfllllllll 2/6 4 I l0 INVENTOR. ig HAROLD K. Fox

BY f l6.5 WMFM AT'roRNE Y5 Unit 3,046,919 AUTOMATIC THREAD CLIPPER FOR BAG END SEWING MACHINES Harold K. Fox, Minneapolis, assignor to Bemis Bro. Bag Company, Minneapolis, Miun a corporation of Missouri Filed Nov. 27, 1959, Ser. No. 855,724 4 Claims. (Cl. 112-11) This invention relates to new and useful improvements in bag top sewing machines and more particularly to such machines including a continuously operating stitching mechanism wherein a chain of stitches connects ad-' jacent bag tops, and which chain of stitches or thread must be cut or severed to free the bag tops from one another.

Conventional bag top sewing machines such as now in common use, usually require an operator to be stationed adjacent thereto to manually guide the chain threads between adjacent bag tops into a suitable thread cutting device located adjacentto the travel path of the bag tops. Such manual feeding of the chain threads into the thread cutter requires the bags to be spaced a considerable distance apart, usually from five to six inches, to permit ample time for the operator to guide each chain thread into the thread cutter without retarding the operation of the sewing mechanism. Such manual guiding of each chain thread into the thread cutter consumes time and, in addition, the relatively wider spacing between the bag tops, as they are progressively fed into the thread cutter, results in a reduction in the number of bag tops which may be sewn in a given length of time.

An important object of the present invention, therefore, is to provide an improved sewing mechanism for such bag top sewing machines which is entirely automatic and does not require the services of an operator for guiding the chain thread between bag tops into the thread cutting means, and whereby the spacing between adjacent bag tops as they are progressively fed through the sewing mechanism in rapid succession, maybe reduced to a fraction of the spacing heretofore usually required between adjacent bag tops, when sewn in bag top sewing mechanisms of conventional construction, thereby resulting in relatively greater economy.

A further object of the invention is to provide in com bination with a bag top sewing head comprising a continuously operating stitching mechanism for sewing the bag tops as they are progressively fed thereto and whereby a chain thread connects adjacent bag tops, of a continuously operating thread clipper located adjacent to one side of the travel path of the bag tops and having means associated therewith for engaging and guiding each chain thread out of its normal path of travel into the thread clipper whereby the chain threads between adjacent bag tops are automatically severed to free the bag tops from one another. 7

A further and more specific object of the invention resides in the novel construction of the thread clipper located at one side of the travel path of the bag tops, in-

cluding a pivoted element located at the opposite side of the travel path and operable by traveling movement of the bag tops through the sewing head to traverse said travel path between adjacent bag tops and thereby guide each chain thread into cutting engagement with the thread clipper.

Other objects of the invention reside in the specific construction of the thread clipper whereby the chain threads between bag tops are not likely to become entangled with the projecting end of the stationary clipper blade, when guided into the thread clipper by the pivoted thread guide; in the construction of the pivoted thread Patented July 31, I962 guide with its bifurcated bag top engaging portion, said bifurcated portion being arranged to slidably engage each 1 bag top under spring pressure and with its bifurcated terminal straddling the row of stitching applied to each bag top, said bifurcated terminal when becoming disengaged from the trailing end of each bag top, engaging the following chain thread and laterally guiding it into cutting engagement with the thread clipper; in the means provided for positively feeding each sewn bag top to a point beyond the thread clipper whereby the sewn bag top may momentarily hesitate in its forward movement, when the feed dog and presser foot become disengaged therefrom, such momentary hesitation of the sewn bag top causing a slackness in each chain thread thereby to facilitate quickly guiding each chain thread into the thread clipper; and in the simple and inexpensive construction of the thread clipper and bag feeding means.

These and other objects of the invention and the means for their attainment will be more apparent from the'following description taken in connection with the accom-' a structure designed to carry out the various objects of the invention, but it is to be understood that the inven-- tion is not confined to the exact features shown, as various changes may be made within the scope of the claims which follow.

In the drawings:

FIGURE 1 is a plan view of a portion of a bag top sewing machine showing the presser foot, feed dog and the needle, and showing two bags passing through the sewing head with the bifurcated terminal of the thread guide engaging a wall of one of the bag tops;

FIGURE 2 is a view similar to FIGURE 1, but show-' thread'clipper, and also showing the unique construction of the stationary knife blade;

FIGURE 5 is a fragmentary sectional view on the line 5-5 of FIGURE 4, indicating in dotted lines the position of the pivoted thread guide and a chain thread, when said thread is moved into cutting engagement with the thread clipper; I

FIGURE 6 is a front face view of the throat plate showing the position of the feed dog with relation thereto;

FIGURE 7 is a face view of the feed dog only;

FIGURE 8 is a view showing the relatively close spacing between adjacent bag tops made possible by'the use of the novel thread clipper, herein disclosed, and showing the chain thread between the two bags severed;

FIGURE 9 is a view similar to FIGURE 7, but showing a feed dog having two vertically spaced forward extensions adapted to cooperate with similar extensions provided on the presser foot to facilitate moving the tops of textile bags through the sewing head; and

FIGURE 10 is a view similar to FIGURE 6 showing the form of throat plate utilized with the feed dog, shown in FIGURE 9.

In the selected embodiment of the invention herein disclosed, there is illustrated in the application drawings a portion of a sewing machine head, generally designated by the numeral 2, comprising a throat plate 3, a feed dog 4, a presser foot 5, and a reciprocating needle 6. The needle 6 is shown secured to an actuating bar or machine.

rod 7, mounted for reciprocal movement, as is well known in the art.

The presser :foot is shown-supported on spaced rods 848, :best shown in FIGURE 3, and 'an actuator 9 is mounted adjacent to the presser 'foot 5 and has its opposite end 11 adapted toactuate a rod 12, which inturn actuates a micro switch (not shown) to start the sewing An adjusting element 13 is shown secured to rod 12 adapted to directly engage a projection 14 on the actuating member 9, as best illustrated in FIGURES 1and2. t

. All of the above described elements are operated in V fimed'relation by a suitable operating mechanism, not

shown "in the drawings, and which has been omitted for thepurpose of simplification. a

. An'important feature of the present invention resides in the means provided for laterally moving each chain'thread 15 between adjacent bag tops out of its normal course of travel into thethread clipper, generally designated by the numeral 10, and best illustrated in"FIGURE 4;

The thread clipper comprises 'a fixed cutter blade 16' and a movable cutter blade 17. Blade 17 is actuated by an arm 18, which in turn is actuated by thet usual operating mechanism of the sewing head, as 'is well known in the'art. The :fixed cutter blade is adjustably secured inposition to a stationary part of the sewing head 2 by a 'lock screw 19. i The two cutter blades, it will be noted,

, are positioned adjacent to the travel pathv of the' bag tops, whereby means must be provided for laterally mow ing each connecting chainthread outpf its norrnal path'of'travel intoposition between the two knife blades of the thread clipper 10,'as clearly indicated in FIGURE 7 4. To obviate any possibility of the chain thread becoming entangled'with the leading end ofthe stationary cutter blade 16, the 'adjacentrend of said cutting blade ment of guide element 21 when released between bag tops to move each chain thread 15 into cutting engagement with the thread clipper 10, as clearly illustrated in FIGURE 2.

Another important feature of the invention 'residesin the means provided for positively fe'e dirig the-trailingend- A e 9P t 1 p n fi yqnd he t ea cl per where y the spring-biased pivoted thread guide 2 l' 1will have ample time to move the chain "thread into .the thread clipper 7 without interference from the following bag top. 7

To thus assure positive movement of the leading bag A to a point beyond the thread clipper, the 'feed dog 4 is shown provided 'with an elongated extension 37 which co-acts withan elongated extension '38 onthegpresser foot 5. The elongated extension 38 of the'presser foot engages theside of :thebagtop opposite from the extension 37 of the feed dogand provides a support therefor, whereby a positive feeding action is imparted to bag gp disengaged from the bag top. a

- It is to be understood that in abagtop sewing machine A -by the feed do'guntil the extensions 37 and- 38 become such .as herein-disclosed, the weight of the filled bags'is usually carried on a continuously traveling conveyon' not shown in the drawings. In-some' instances the"conveyo'r' may travel at the samespeed asthxt-of the -bag tops as they are 'fed through the 'sewing headby'the feed dog 4 1 and presser foot 5. However, to facilitate the operationof severing each chain thread between adjacent bag tops,

thesewing-head may be operated at a slightly higher I travelingspeed than the conveyor, whereby when theflt-rail? ing end of each bag top moves out of enga'gement with is made very 'blunt and slightly rounded tlius' to perrnit the chain thread to readily enter between the two knife bladesduring actuation of the movable cutter blade 17. A

.: 'To thus a guide each chain thread '15 into cutting engagement with the thread clipper 10, a threadguide element, generally designated by the numeral 21, is :pivoted to the presser foot 5, by a/pivot pin 22, best illustrated in'FIGURE'i 4. The guide element 21 isprovidedwith an enlarged bore for receiving'a flanged bushthe extensions 37 and 38, respectively, of the feed-dog [and presser foot 5, the top of bag A will hesitate slight- 1y in its forward movement with reference-tothe following bag top B, whereby the connecting chain thread 15 between :bag tops A and B 'will'develop a slight slacknerss which facilitates moving said chains-thread into cutting ing 23 the flanged end ofwhich is:engaged by the head i 24 of pivot pin 22, andwhereby the pivot pin may be firmly secured toan overhangingportion 25, provided on the presser foot '5, as clearly illustrated in FIGURES l, 2 and 4. By thusmountin'g the' gulide element 21 it is always freely rotatable upon the bushing23;

A spring 26 is coiled about the. flanged end or the bushing 23, and has one, end anchored in -%an aperture 27 provided in the guide element 21. The-opposite {end of the spring 26 iis engaged with oneend of a stud '28 adjustably mountedin the overhanging "portion725f'of. the

presser foot, as shown in FIGURES 1, '2 and 14. 7

A "stud 28 "isshown provided with an annular shoulder 20, and has a reduced threaded iterminal'rec'eived in an elongated opening or slot 29 provided in the part 25 of the presser foot. 5, whereby the stud'may readily be ad justed in slot 29 vby manipulation of the nut 31, thereby to vary thetensioninspring'26. i 1

Another important featureof the invention resides in thejspecific construction of the pivoted guide element 21.

As best shown in FIGURE 4, it comprises a bifurcated ing head.

engagement with the thread clipper to assure positive severing of each chainthread, as the bag tops are'fed progressively through the sewing head.

' Theforward end of the feed dog 4 is preferably cut away or grooved, as indicated at 41 in FIGURES 1, 2,6 7

and 7, thereby ,to permit each'ch'ain thread 15 to be more readily fed intothe threadclipper-l flbyet-he pivoted guide element 21, as shown more particularly in FIGURE 2."

In FIGURE 9 there isshown a feed dog 4a or sugnfly modified coinstru'etiori designed nrore particularly for use a with a throat platei3a, .such'as illustrated in FIGURE 10. The feed dog 4a, 'it will be noted, comprises two vertically spaced extensions 37a and 37b adapted tolicooperate with extensions provided on the presser :foot above and below the row of stitching, thereby to assure apositive feeding a movement of the trail-ingend or each bag toptto apoint beyond the thread clipper 10.

' Throat plate 3a differs from :the' one for receiving ithel feed dog-are of uniform length, as

shown in FIGURE 10, to accommodate the two-forward extensions 37a and 37b on Ithe-feed dog; 'l he pres'ser foot used in conjunction \m'th thezfeed dog and than plate shown in FIGURES 9-and 10?is also provided vertic lly Spaced elongated extensions, lpartially shown V inthedrawings, adapted to cooperate withthe extensions 37a;and 37b of feed dog 4a to engageand positively feed the trailing end of each textile bag top th'roujgh the sew- In the operation of the apparatus, the flattenedhag tops are progressively fed ,throughthe sewing head -in closely spaced relation. The pivoted guide'element 21 is' normally positioned as shown in FIGURE 2, when the sewing ,head is empty of bag tops because of the action ofspring 26. Asbag Aproceedsthrough the sewinghead' it engages .the rounded surface 39.0f'guide element 21, whereby the guide element is moved out of the travel path of the bag tops against the tension of spring 25 by each shown-inFIGURE" 6 in that theelongated openings orslotsprovided therein bag top. The bifurcated terminal 32 of the pivoted element 21 then rides over the adjacent wall of bag top A, with its bifurcated terminal straddling the row of chain stitching in said bag top.

The bifurcated terminal 32 of the pivoted guide element 21 assures that each chain thread 15 is accurately and positively guided into the thread clipper without failure. The groove 41 in the forward end portion of the feed dog for receiving each chain thread, when engaged by the bifurcated or forked terminal of the guide element 2 1, permits each chain thread 15 to enter the thread clipper 14 at a more desirable angle, whereby the chain thread cannot be forced out of the clipper when the clipper blades 16 and 17 engage the thread, even if such blades have been partially dulled from use.

The positive feeding of each bag top to a point beyond the thread clipper, and the relatively closer spacing of the bag tops, as they are progressively fed through the sewing head, results in increased production in that a relatively greater number of bag tops may be sewn in a given length or time, than is possible with bag top sewing machines as now commonly constructed.

The improved sewing head herein disclosed has proven ntremely practical and eflicient in actual use, as it may be operated at high speed Without failure with a resultant reduction in operating and maintenance costs.

it is apparent that many modifications and variations of this invention as hereinbefore set forth may be made without departing from the spirit and scope thereof. The specific embodiments described are given by way of example only and the invention is limited only by the terms of the appended claims.

I clahn as my invention:

1. In a machine for sewing the open tops of filled bags, a sewing head including a stitch-forming mechanism for continuously forming a chain stitch on said bag tops and a chain thread connecting adjacent bag tops, a presser foot, and a feed dog cooperable with said presser foot to progressively advance the bag tops along a pre ctermined travel path in closely spaced relation, a thread clipper spaced laterally from one side of said travel path comprising coacting cutting blades disposed at right angles to said path, means for positively advancing the trailing end of each bag top to a point beyond the thread clipper, said means comprising elongated coacting bag top en gaging extensions provided respectively on the presser foot and said feed dog, a pivoted guide element located at the opposite side of said travel path being provided with spring means to constantly urge said pivoted guide ele ment in a direction to traverse said travel path, said guide element having a notch therein which nonnmly rides said chain stitch being formed on said bag tops and which is adapted to guide each chain thread between adjacent bag tops into immediate cutting engagement with said blades when said pivoted guide element momentarily traverses said travel path to free the bag tops from one another, actuation of said pivoted element being controlled by movement of the bag tops through said sewing mechamsm.

2. The combination with a machine for sewing the open tops of filled bags, including a sewing head having comprising elongated coacting ba g top engaging extensions provided respectively on the presser foot and feed dog, a spring-biased guide element having a notch therein which normally rides said chain stitch being formed on said bag tops, said guide element being pivotally mounted to momentarily traverse said travel path between adjacent bag tops to engage and guide each connecting chain thread into cutting engagement with the thread clipper to free the bag tops from one another, actuation of said guide element being controlled by movement of the bag top through said sewing mechanism.

3. In a machine of the class described, a sewing head including a throat plate, a stitch-forming mechanism for continuously forming a chain stitch on said bag tops and a chain thread connecting adjacent bag tops, a presser foot, and a feed dog cooperable with said presser foot to progressively advance the bag tops along a predetermined travel path in closely spaced relation, a thread clipper spaced laterally from one side of said travel path and comprising coacting cutting blades disposed at right angles to said travel path, one of said knife blades being fixed and the other being movable relative thereto, said f xed blade having an elongated blunt end portion disposed adjacent to said travel path and so positioned with respect to said movable knife blade that the connecting chain threads between adjacent bag tops may readily be guided into cutting engagement with said knife blades, means for positively advancing the trailing end of each bag top to a point beyond the thread clipper, said means comprising elongated coacting bag top engaging extensions provided respectively on the presser foot and said eed dog, and means actuated by movement of the bag tops to the sewing head including a pivoted guide element having a notch therein which normally rides said chain stitch being formed on said bag tops and which is adapted to guide each chain thread between bag tops into immediate cutting engagement with the blades of the thread cutter.

4. In a machine for sewing the open tops of filled bags, a sewing head including a throat plate, a stitch-forming mechanism, a presser foot, and a feed dog cooperable with said presser foot to progressively advance the bag tops along a predetermined travel path in closely spaced relation and whereby a chain thread connects adjacent bag tops, a composite thread clipper spaced laterally from one side of said travel path, a pivoted guide element located at the opposite side of said travel path, said pivoted element being operable by movement of the bag tops through the sewing head to momentarily traverse said travel path between bag tops and engage and guide each chain thread into immediate cutting engagement with said thread clipper, means for positively advancing the trailing end of each bag top to a point beyond the thread clipper, said means comprising elongated coacting bag top engaging extensions provided respectively on the presser foot and said feed dog, means causing each bag top to momentarily hesitate in its traveling movement as the feed dog and presser foot disengage the trail ing end thereof, such momentary hesitation of each bag top causing .a slack to develop in each chain thread whereby said guide elements may readily move each chain thread into immediate cutting engagement with the thread clipper.

References Qited in the file of this patent UNITED STATES PATENTS 2,376,417 Chudner May 22, 1945 2,569,396 Bates Sept. 25, 1951 2,630,086 Kindseth et a1. Mar. 3, 1953 2,670,700 Kindseth Mar. 2, 1954 

